Recapping Bertha's breakthrough

Posted on Apr 6 2017 12:43 PM

Bertha's 9,270-foot journey beneath Seattle ended in dramatic fashion on Tuesday as the machine broke through into her disassembly pit near Seattle Center:

On Tuesday morning all that stood between Bertha and daylight was the five-foot-thick concrete wall at the south end of the disassembly pit. Crews from Seattle Tunnel Partners began mining around 8 a.m. on Tuesday and broke through shortly before noon.

The view looking south at the breakthrough wall of the disassembly pit

Bertha beginning to make her move

Bertha's cutterhead at rest after breakthrough. The braces will be removed before the machine moves further into the pit.

WSDOT shared updates from the scene on Twitter, Facebook and Periscope, and hosted a livestream. (Roughly a half million people tuned into WSDOT's web channels to watch breakthrough, and another one million watched the livestream via local news outlets.)

What comes next?

In the coming weeks, STP will remove the braces in the disassembly pit and move Bertha into her final position in the pit. You can watch that work on the Bertha's Breakthrough page. The machine will be taken apart and removed from the tunnel.

There is much work left to be done before the tunnel opens to traffic, currently scheduled for early 2019. Our recent program spotlight explains the interior structures and tunnel systems work that cres have already begun.

We will be transitioning the Bertha's Breakthrough page in the coming weeks to a page that tracks this progress. As always, follow the program Twitter feed and this website for updates on the work to replace the Alaskan Way Viaduct.